Platform

ABSTRACT

This invention relates to a traveling suspended platform, for use with vertical work surfaces, which is stabilized against oscillation or sway while exerting relatively little force on the vertical work surface.

EJfiEe States Ptent Melton 1 Feb. 22, 1972 [54] PLATFORM [56] ReferencesCited [72] Inventor: Donald F. Melton, 899 West Highway 96, UNITEDSTATES PATENTS 55112 2,645,531 7/1953 Rector ..182/37 [22] Filed: Sept.12, 1969 2,692,168 10/1954 Gregory 182/13 pp No: 85 ,519 2,710,4186/1955 Putnam ..l82/l28 Primary Examiner-Reinaldo P. Machado Attorney-J.Vincent MartinJoe E. Edwards and M. H. (jay 52 11.5.0 ..1s2/19, 182/37,182/142, [571 ABSTRACT 182/1 This invention relates to a travelingsuspended platform, for [51] lnt.Cl ..E04g 3/10 use with vertical worksurfaces, which is stabilized against [58] Field of Search 182/12, l3,19, 142, 36, 37, oscillation or sway while exerting relatively littleforce on the 182/229, 14 vertical work surface.

11 Claims, 5 Drawing Figures bul q 1:2 1! 22 2 q :1; i if 2/ 15/ :11 I

PLATFORM Suspended platforms are a widely used means for affordingworkmen access to vertical work surfaces. In some operations, such asfor example the painting, lining, or insulating of large storage tanks,a traveling suspended platform moving horizontally around the tank ineither stepwise or continuous movement, would provide an advantageousmeans for moving workmen and supplies from one wall section where workhas been completed to another section where it has not.

However, suspended platforms, and particularly traveling suspendedplatforms, have the disadvantage of instability. They tend to swing oroscillate in reaction to the movement of the workmen or the overheadsupport apparatus. These oscillations make work more difficult and maybe dangerous to the workmen. Also, the instability problem increaseswith increased distance from the overhead support to the platform.Since. in some storage tanks, as for example the cryogenic storage tankdisclosed in the US Pat. to Smith et al., No. 3,196,622, the tank wallsmay be 60 feet or more in height, the problem of eliminating instabilityin the platform should be solved if traveling suspended platforms are tobe used. It is also desirable that the method used to stabilize theplatform not require the exertion of substantial forces on the tankwalls, since in tanks such as the Smith cryogenic storage tank the wallsmay be covered by lining or insulation material which will not supportheavy loading.

It is, therefore, an object of this invention to provide a suspendedplatform which may be used with a wall of any height without beingsubject to dangerous swaying or oscillations.

Another object is to provide a suspended platform adapted to travelhorizontally across a wall at a constant rate of speed withoutsubstantial swaying or oscillation.

Another object is to provide such a platform which requires nostructural connection to the wall, which exerts relatively littlepressure on the wall, and which will travel freely therealong withoutdamaging delicate coatings or insulation which may be on the wall.

Another object is to provide a suspended platform which is adapted totravel peripherally around the interior of a circular storage tankhaving a layer of insulation material thereon at a constant rate ofspeed without dangerous swaying or oscillation, and without exertingsufficient pressure on the tank walls to damage the insulation thereon.

These and other objects and advantages of the invention will becomeapparent from the drawings, specification and claims.

In the accompanying drawings which illustrate the preferred embodimentof the present invention, and wherein like numerals indicate like parts:

FIG. 1 is a view in elevation ofa platform and overhead trolley inaccordance with the present invention;

FIG. 2 is a plan view ofthe platform ofFlG. 1;

FIG. 3 is an end view of the same platform;

FIG. 4 is an enlarged sectional view taken along line 44 of FIG. 3; and

FIG. 5 is a schematic illustration of the automatic limit switch used onthe platform of the present invention.

The traveling suspended platform of the present invention is well suitedfor use in the construction of large insulated storage tanks, such asthe cryogenic storage tank disclosed in the above referenced Smithpatent. For convenience and clarity, this disclosure of the preferredembodiment of the present invention is made in relation to its use inthe construction of such a cryogenic storage tank, although it may beutilized in conjunction with any wall.

An arcuate section of the circular wall of a large storage tank isindicated generally at 10, the concave side of wall representing thetank interior and the convex side representing the tank exterior. Asshown, the wall 10 comprises two layers, a structural layer 10a ofconcrete or other suitable material, and a layer of insulation material10!; disposed on the concave side of the structural layer 10a. Theapparatus of the present invention may be viewed as being used to applyto the insulation layer 10b a vapor liner'material, a second layer ofinsulation material, etc,

Disposed on the concave side of wall 10, but spaced therefrom, aresuitable platform retaining means. it is preferred that these consist ofa plurality of vertical posts 12 spaced from each other and spacedapproximately equidistant from the tank wall 10.

Disposed between the wall 10 and the platform retaining means is anoverhead track 13, such as an l-beam, on which is supported a trolley;indicated generally at 14. The trolley has two end trucks 15 which rideon the track 13 with rollers 16. In addition to the rollers 16, the twoend trucks 15 may mount other rollers (not shown) which stabilize thetrolley by riding two outrigger beams (also not shown) running parallelto and on each side of the track 13. Power means for moving the trolleyl4 horizontally along track 13 may be provided by a traction unit 17mounted at one end of the trolley 14 and having a variable speed motor18, and rollers 19 adapted to engage the track 13.

Spaced below the trolley is a platform, indicated generally at 20, whichis basically rectangular in shape and is preferably constructed ofaluminum for lightness. The platform 20 carries a safety railing 21, acentral mast 22 and end masts 23 and 23a.

Means for suspending the platform 20 from the trolley 14 may be providedin the form of flexible metal cables 24. In the preferred form, two suchspaced metal cables 24 depend from each of the two trolley end trucks l5and have their lower ends wrapped on the drums of four hand winches 25which are secured to the deck of platform 20. The platform 20 istherefore suspended in the annular region defined by the circular tankwall 10 and the concentric platform retaining means within the tank. Theplatform will travel horizontally around the annular region as thetrolley 14 moves along the overhead track 13; and the platforms verticalposition may be readily adjusted by the operation of hand winches 25 toincrease or decrease the effective length of suspension cables 24.

Stabilizing means for the suspended platform is provided by expansiblemeans mounted on the platform and adapted to simultaneously engage thewall 10 and the platform retaining meansin this case the spaced verticalposts 12. In the preferred form, these expansible means comprise twounits: A wall-engaging unit, indicated generally at 26, and adapted toengage the tank wall 10; and a roller carrier beam 27 disposed on theopposite side of platform 20 and adapted to engage the spaced verticalposts 12. One of the wall-engaging unit 26 and beam 27, preferably thewall-engaging unit, is fixed to the platform.

The wall-engaging unit 26 includes an elongate member 29 preferablydisposed with its horizontal axis parallel to that of the platform. Themember 29 is rigidly attached to a crossbeam 28 mounted on the platformcentral mast 22 a suitable distance above the platform deck. Twopneumatic tire wheels 30 are mounted, one near each end of the elongatemember 29 on the side facing the tank wall 10, and are adapted torollably engage the insulation layer 10b of tank wall 10 as the platformmoves horizontally around the tank.

The second part of the platform stabilizing means is a roller carrierbeam 27 which is movably mounted on the platform and adapted to engagethe vertical posts 12. The beam 27 is elongated and arcuate, beingcontoured to follow the line of posts 12, and is of a length sufficientto be in contact with at least two of the posts 12 at all times, andpreferably with three posts during transition from post to post. Rollercarrier beam 27 has disposed along its edge adjacent the posts 12 aplurality of small rollers 32 which rollably engage the posts 12 as theplatform moves around the tank. Only a few of these rollers are shown,but they, extend the length of beam 27. A larger roller 33 is mounted ateach end of beam 27 to insure proper rolling engagement with each post12 as the platform moves into engagement with a new post.

The roller carrier beam 27 is movably mounted on the platform centralmast 22 and end masts-23 and 23a for free movemeat toward or away fromthe vertical posts 12. Referring to FIGS. 3 and 4, a bracket 34extending perpendicularly from the back of beam 27 has a lower flange 35which is confined between grooved bracket guides 36 and 36a mounted oncrossbeam 28 of central mast 22. Thus, the bracket 34 can move freelyonly in the direction of the longitudinal grooves in the bracket guide36. The beam 27 is attached to bracket 34 by a pivot 34a. Thisarrangement permits free movement of beam 27 toward or away from thevertical posts 12 and assures that no torque will be exerted by beam 27to turn the platform relative to the wall. The end masts 23 and 23a,mounted one at each end of the platform 20, support the extremities ofroller carrier beam 27. Rollers, not shown, ride on the top surface ofmasts 23 and 230. These rollers allow beam 27 to move freely in thehorizontal plane but not vertically.

Pressure exerting means are provided for resiliently urging theplatform's expansible means away from each other and into simultaneousengagement with the tank wall and the vertical posts 12, so as tomaintain the platform in a stable position. In the preferred form, thisis accomplished with a pulley-and-weight arrangement. A pulley 37 ismounted on the bracket guides 36 and 36a. A flexible tension member 38,one end of which is attached to the free end of the roller carrier beambracket 34, is passed over pulley 37 and on its lower end are hungweights 39. This creates a tension in line 38 which urges the rollercarrier beam 27 away from the platform and toward the posts 12 with aforce corresponding to the amount of weight 39. An equal force in theopposite direction is exerted on the platform 20 by the pulley 37. Thisreaction force urges the platform toward the tank wall 10 and therebymaintains the wheels of the wall-engaging unit in constant engagementwith the insulation layer 10b of tank wall 10. The force which theroller carrier beam 27 exerts against the vertical posts 12 and theforce which the wall-engaging wheels 30 exert against the insulationlayer 10b can be readily adjusted merely by changing the weight 39suspended from pulley 37.

An idler wheel 31 is mounted near each end of the platform 20 on theside adjacent the tank wall 10 to prevent the platform body fromengaging and damaging the insulation layer 1011 should the platformmomentarily tip.

Although the simultaneous engagement of the tank wall and theplatform-retaining means by expansible means associated with theplatform will greatly stabilize the platform, providing stabilizationwhen the platform and trolley are moving circumferentially with respectto the wall, against platform oscillation may be obtained by driving theplatform 20 horizontally along the tank wall 10 at the same rate as thetrolley 14 moves along the overhead track 13. While this may beaccomplished in any desired manner, we prefer to accomplish it by usinga variable speed motor 40 mounted on the wall-engaging unit 26 to drivethe pneumatic tire wheels 30 which are in contact with the tank wall 10.The variable speed motors on the trolley and the platform should be setat speeds such that the trolley and platform will move about the tank atapproximately the same rate.

To assure perfect synchronization of the trolley and platform, sensingmeans may be provided, associated with the flexible suspension cables24, which are adapted to sense when the platform body is out of plumbwith respect to the overhead trolley 14 and automatically adjust therelative rates of travel of the trolley and the platform to bring themback into plumb relationship. This is accomplished with limit switches41 and 43, indicated schematically in FIG. 4. The switches are disposedone on each side of one of the platform suspension cables 24 and areactuated by contact with the cable. As long as the platform hangs plumbwith the trolley, neither switch is operated, If the trolley is drivenfaster than the platform, the platform lag switch 41 will be contactedby cable 24 and will operate through a voltage-varying device indicatedgenerally at 43 to slightly reduce the speed of the trolley motor 18. Ifthe trolley is operating too slowly, the platform lead switch 42 will becontacted by cable 24 and will operate through the voltage-varyingdevice 43 to slightly speed up the trolley motor 18. Of course, thechoice of whether to vary the speed of the trolley motor or the platformmotor is arbitrary.

From the foregoing it can be seen that the present invention constitutesan improved type of traveling suspended platform wherein the platformhas expansible means for simultaneously engaging both the wall and aretaining means to greatly reduce platform instability while exertingrelatively little force on the wall; and the platform and its overheadsupport means may be driven at the same speed to virtually eliminatesway and oscillation of the platform.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof, and various changes in the size,shape and materials, as well as in the details of the i]- LII lustratedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

1. An apparatus comprising:

A trolley adapted to be supported on an overhead track disposed betweena substantially vertical wall and substantially verticalplatform-retaining means spaced horizontally from said wall;

a platform;

means for suspending said platform from said trolley, said platformbeing suspended between said wall and said retaining means;

stabilizing means for said platform comprising,

expansible means on said platform for simultaneously engaging said walland said retaining means, and

pressure-exerting means for resiliently urging said expansible meansinto simultaneous engagement with said wall and said retaining means.

2. The apparatus of claim 1 wherein:

said expansible means comprises,

means fixed on the platform for engaging one of the wall and theretaining means, and

means movably mounted on the platform for engaging the other of the walland the retaining means.

3. The apparatus of claim 1 wherein said expansible means carries rollermeans to rollably engage said wall and said retaining means.

4. The apparatus of claim 1 wherein said trolley has powered motivemeans associated therewith for moving said trolley along said overheadtrack.

5. An apparatus comprising:

A trolley adapted to be supported on an overhead track disposed betweena wall and a retaining means spaced from said wall;

powered motive means associated with said trolley for moving saidtrolley along said overhead track;

a platform;

flexible means for suspending said platform from said trolpoweredwall-drive means fixed to said platform and adapted to engage said walland urge said platform substantially horizontally therealong;

roller-carrier means movably mounted on said platform and adapted torollably engage said retaining means;

pressure-exerting means for resiliently urging said walldrive means andsaid roller-carrier means away from each other and into engagement,respectively, with said wall and said retaining means; and

sensing means associated with said flexible means and adapted to sensewhen said platform body is out of plumb with respect to said overheadtrolley and automatically adjust the relative rates of travel of saidtrolley and plat- 'form to bring said trolley and said platform backinto plumb relationship.

6. The apparatus of claim 5 wherein:

Said sensing means comprises limit switches disposed on opposite sidesof said flexible means and adapted to be actuated by contact with saidflexible means as it moves from a vertical to a nonvertical position.

71 A traveling platform for use with a vertical wall, comprising aplatform,

platform-retaining means comprising a plurality of substantiallyvertical posts spaced from each other in a line and spaced approximatelyequidistant horizontally from said wall,

a trolley movably supported on a track disposed over said platform andbetween said wall and said retaining means,

means for suspending said platform from said trolley and between saidwall and said retaining means,

stabilizing means for said platform comprising expansible means on saidplatform for simultaneously engaging said wall and said retaining means,and

pressure exerting means for resiliently urging said expansible meansinto simultaneous engagement with said wall and said retaining means.

8. The apparatus of claim 7 wherein said expansible means comprises,

means fixed on the platform for engaging one of the wall and theretaining means, and means movably mounted on the platform for engagingthe other of the wall and the retaining means. 9. The apparatusaccording to claim 8 wherein said means to engage said retaining meansincludes,

an elongated beam longitudinally contoured to follow the line of saidspaced posts, the length of said beam being sufficient to be in contactat all times with at least two of said posts. 10. The apparatusaccording to claim 7 wherein, said expansible means carries roller meansto rollably engage said wall and said retaining means. 11. The apparatusofclaim 7 wherein, said trolley has powered motive means associatedtherewith for moving said trolley along said overhead track.

1. An apparatus comprising: A trolley adapted to be supported on anoverhead track disposed between a substantially vertical wall andsubstantially vertical platform-retaining means spaced horizontally fromsaid wall; a platform; means for suspending said platform from saidtrolley, said platform being suspended between said wall and saidretaining means; stabilizing means for said platform comprising,expansible means on said platform for simultaneously engaging said walland said retaining means, and pressure-exerting means for resilientlyurging said expansible means into simultaneous engagement with said walland said retaining means.
 2. The apparatus of claim 1 wherein: saidexpansible means comprises, means fixed on the platform for engaging oneof the wall and the retaining means, and means movably mounted on theplatform for engaging the other of the wall and the retaining means. 3.The apparatus of claim 1 wherein said expansible means carries rollermeans to rollably engage said wall and said retaining means.
 4. Theapparatus of claim 1 wherein said trolley has powered motive meansassociated therewith for moving said trolley along said overhead track.5. An apparatus comprising: A trolley adapted to be supported on anoverhead track disposed between a wall and a retaining means spaced fromsaid wall; powered motive means associated with said trolley for movingsaid trolley along said overhead track; a platform; flexible means forsuspending said platform from said trolley; powered wall-drive meansfixed to said plAtform and adapted to engage said wall and urge saidplatform substantially horizontally therealong; roller-carrier meansmovably mounted on said platform and adapted to rollably engage saidretaining means; pressure-exerting means for resiliently urging saidwall-drive means and said roller-carrier means away from each other andinto engagement, respectively, with said wall and said retaining means;and sensing means associated with said flexible means and adapted tosense when said platform body is out of plumb with respect to saidoverhead trolley and automatically adjust the relative rates of travelof said trolley and platform to bring said trolley and said platformback into plumb relationship.
 6. The apparatus of claim 5 wherein: Saidsensing means comprises limit switches disposed on opposite sides ofsaid flexible means and adapted to be actuated by contact with saidflexible means as it moves from a vertical to a nonvertical position. 7.A traveling platform for use with a vertical wall, comprising aplatform, platform-retaining means comprising a plurality ofsubstantially vertical posts spaced from each other in a line and spacedapproximately equidistant horizontally from said wall, a trolley movablysupported on a track disposed over said platform and between said walland said retaining means, means for suspending said platform from saidtrolley and between said wall and said retaining means, stabilizingmeans for said platform comprising expansible means on said platform forsimultaneously engaging said wall and said retaining means, and pressureexerting means for resiliently urging said expansible means intosimultaneous engagement with said wall and said retaining means.
 8. Theapparatus of claim 7 wherein said expansible means comprises, meansfixed on the platform for engaging one of the wall and the retainingmeans, and means movably mounted on the platform for engaging the otherof the wall and the retaining means.
 9. The apparatus according to claim8 wherein said means to engage said retaining means includes, anelongated beam longitudinally contoured to follow the line of saidspaced posts, the length of said beam being sufficient to be in contactat all times with at least two of said posts.
 10. The apparatusaccording to claim 7 wherein, said expansible means carries roller meansto rollably engage said wall and said retaining means.
 11. The apparatusof claim 7 wherein, said trolley has powered motive means associatedtherewith for moving said trolley along said overhead track.